Well it's quite possibly the biggest reason out there, at least for me (kink, pr0n and gay sex are the other ones LOL), but fixits will always be there when something goes wrong, yay! :) Actually the intro to the archive I posted above is something along the lines of "we don't like it, so we'll write fic and fix it".
Sadly I think that long time fandoms usually have the problems of writers going away, so even if some of the fans are still there, there's no one to write the stories.
*pouts* Way too many big bangs have started in the last year, but most of them nowadays are not pairing specific but character specific, not sure I like that very much *sigh* Am sure that something new could be started? If people were interested? I don't know what went on with the original organizers, but since they are not interested any more, that should prohibit someone else from trying for Snarry BigBang should it?